Embodiments of the disclosed technology relate to an array substrate, a manufacturing method of the array substrate, and a liquid crystal display.
Liquid crystal displays (LCDs) are currently common flat panel displays, and thin film transistor liquid crystal displays (TFT-LCDs) are the main kind of LCDs.
A liquid crystal panel of a LCD is generally formed by assembling together an array substrate and a color filter substrate. The array substrate typically comprises a substrate, on which gate lines and data lines intersecting with each other are provided to define a plurality of pixel units arranged in a matrix form. A thin film transistor (TFT) switching element and a pixel electrode are provided in each of the plurality of pixel units. As shown in FIGS. 1A and 1B, for example, the TFT switching element comprises a gate electrode 3, an active layer 6, a source electrode 7 and a drain electrode 8. The gate electrode 3 is electrically connected to one of the gate lines or as a part of one of the gate lines and is formed on a base substrate 1, the active layer 6 is provided over the gate electrode 3 with a gate insulating layer 4 sandwiched therebetween, one end part of the source electrode 7 and one end part of the drain electrode 8 are provided to be opposite to each other on the active layer 6 and a channel region is defined between the source electrode 7 and the drain electrode 8. When the gate electrode 3 is supplied with a high voltage for turning on the switching element, electrical conduction is established between the source electrode 7 and the drain electrode 8 through the active layer 6.
In the related arts, conductive patterns on the array substrate are generally each formed by using an exposing process with a mask. For example, the source electrode and the drain electrode are formed from the same material layer by using one patterning process with a single mask. Because of the processing parameters of the patterning process, such as, sizes of patterns of the mask, precision of exposing and etching and so on, a channel length L between the source electrode and the drain electrode (distance between the source electrode and the drain electrode) has a minimum size limit. The conventional minimum value of the channel length is 4 μm. However, the conduction characteristics of the channel are depended on the channel length. The longer the channel is, the larger the size of the TFT is in order to ensure the same performance, which leads to reduced aperture ratio of one pixel unit. Therefore, reduction of the channel length is one problem to be solved.